March 2, 2006 3D Mesh Coding and Transmission Lihang Ying Department of Computing Science University of Alberta.

March 2, 2006

3D Mesh Coding and 3D Mesh Coding and TransmissionTransmission

Lihang YingDepartment of Computing Science

University of Alberta

L.Ying, 3D Mesh Coding and Transmission, 2006.

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OutlineOutline

3D Mesh Data3D Mesh Coding

– Valence-Driven Approach

Error-Resilient 3D Mesh Coding and Transmission– Multiple Description Coding

Proposed Research


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3D Mesh Data3D Mesh Data

Geometry:– 3D positions (x-y-z coordinates) of vertices– Coding: 1)Quantization, 2)Differential Coding,

3) Entropy Coding

Connectivity:– How vertices are connected

• Raw data: vertex indices of each face• Large redundancy

– Main Focus of 3D Mesh Coding

Photometry– Colors,Normals,Texture


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3D Mesh Coding3D Mesh Coding

Since early 1990s Up-to-date Survey: [PKK05]

VRML V.2 and MPEG-4 Standard

State-of-the-art Method


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Valence-Driven ApproachValence-Driven Approach

Encoding

Thick line: active lists Dashed line: visited edge Dark point: focus

Encoding Stream: add 6, add 7, add 4, add 4, add 8, add 5, add 5, add 4, add 5, split 5, add 4, add 4, add dummy 6, add 4

add 6, add 7, add 4 add 4 add 8

add 5 add 5 add 4add 5

split 5 add 4 add 4 add dummy 6

add 4


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Valence-Driven ApproachValence-Driven Approach

Decoding

Encoding Stream: add 6, add 7, add 4, add 4, add 8, add 5, add 5, add 4, add 5, split 5, add 4, add 4, add dummy 6, add 4

Thick line: active lists Dashed line: visited edge Dark point: focus

add 6, add 7, add 4 add 4 add 8 add 5 add 5

add 4 add 5split 5

add 4 add 4 add dummy 6

add 4


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Progressive Valence-Progressive Valence-Driven 3D Mesh CodingDriven 3D Mesh Coding

–


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Connectivity Coding is Connectivity Coding is Sensitive to Error Sensitive to Error

– Previous codes impact all subsequent codes.

– Example: one-code error in Edgebreaker method [Rossignac99] results (the right):


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Error ResilienceError Resilience

Error-Resilient Transmission [AAR05]

– Unequal Error Protection– Interleaved Packets

Piece-based Error-Resilient Coding [YKK01]

– Divide mesh into pieces, encode piece by piece, then encode connectivity between pieces.


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Progressive Coding– Enhance layers depends on base layers

Piece-based Error-Resilient Coding– Not friendly to Perceptual Quality

Multiple Description Coding– Each description can be encoded

independently– More descriptions received result

higher quality.– Less efficient

Multiple Description Multiple Description Coding(1)Coding(1)


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Multiple Description Multiple Description Coding(2)Coding(2)Existing Work [JWC04]

– Idea:• Only split the geometry (vertex position)

data into descriptions• Transmit the connectivity of the entire mesh

via a high quality channel.

– How to split vertices into descriptions • Should be spaced evenly in the mesh for

interpolating missed vertices• Construct a vertex spanning tree and assign

each vertex at level l into i-th description.


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Multiple Description Multiple Description Coding(3)Coding(3)Existing Work [JWC04]


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Proposed ResearchProposed Research

Objective– With packet loss: wireless network– No retransmission: real-time

applications– No error protection– Perceptual quality friendly

Multiple Description Connectivity Coding


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Will Improve on Valence-Will Improve on Valence-Driven ApproachDriven Approach

With trivial size and be kept in all descriptions

Or, can be interpolated

add 6, add 7, add 4 add 4 add 8 add 5 add 5

add 4 add 5split 5

add 4 add 4 add dummy 6

add 4


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The EndThe End

Thank you!

March 2, 2006 3D Mesh Coding and Transmission Lihang Ying Department of Computing Science University of Alberta.

Documents

d mesh coding slide

connectivity coding

progressive coding

differential coding

d mesh data geometry

entire mesh

entropy coding connectivity

texture slide